Since some of our customers are having issues delivering email to Hotmail, and we've been pulling out our hair trying to figure out what is going on, I'd thought I'd post something here, and keep this thread up top to help others out - customers or competitors alike.
Various threads and links taken off NANOG list:
Does anyone have a clue why hotmail is appearantly blocking certain IP ranges ?
I provided a new server for a customer in his own IP subnet which is a part of a /20 we announce, but for some reason all mail sent to @hotmail.com addresses disappears.
He has another server in a /24 we announce which is still part of another network and that works like a charm.
None of our subnets are blacklisted in any spamfilter I can find, so i'm a bit puzzeled on what's up here.
If any hotmail netadmin is reading this list, can you please check if 126.96.36.199/26 is blocked in any way (It's part of 188.8.131.52/20 originating from AS39556)
According to the mailserver logs all the mail is properly accepted by the hotmail relays, never to be seen again after that.
I've had the same issue with hotmail when email originates from
184.108.40.206/24. any mail sent from a server within that netblock is
properly accepted by hotmail, given a queue id, but disappears and is
if anyone from hotmail has a clue as to what's going on, it would be
thanks much ...
hotmail reportedly installed some new spam control lately.
many ISPs and ESPs are reporting problems similar to what you describe
(my employer is having such deliverability problems, for one.)
SPF records, signing up for the MSN/Hotmail feedback loop, and opening
a ticket with hotmail support are all things you can do. effectiveness
is not guaranteed, and it's taking hotmail 3-4 days to respond to new
tickets, they appear to be swamped.
Yeah, Hotmail's spam filtering recently got very aggressive. The short
version is that they are being pounded so hard by botnets and other
malicious spam/phish delivery vectors that IPs that have never sent
mail to Hotmail users start out with a negative reputation in
Some info (admittedly, not too detailed, but it's all I could find handily):
Short version of what can be done:
- Ensure any host sending mail has working forward/reverse DNS.
- Start signing mail with Sender ID.
- Contact Hotmail here: http://tinyurl.com/2byyts
- Wait and hope for a response.
It's impacting a lot of folks right now, from what I can see. Hotmail
has been very slow to address (or even respond) in some instances. I
theorize that this is because they are receiving a lot of contact
about this issue, but certainly don't know that for sure.
I'll update this as I read more/learn more/etc.